[wsfii-discuss] Interesting URL

Fri Dec 16 12:08:16 UTC 2005

Hi Karel,

On 12/16/05, Karel Kulhavy <clock at twibright.com> wrote:
> Knowledge of the Shannon's law saves time reading these articles.

Looking at their FAQ (and yet still completely ignorant of these issues):

DEFINITIONS - xMaxTM, xG Flash SignalingTM
Questions:

1.  Is the name xG meant to imply a comparison with 3G wireless technology?
2.  What is xMax?
3.  What is xG Flash Signaling?
4.  What is Index-NTM?
5.  What is VaribandTM?
6.  What is S/Nr?
7.  What is Shannon's Law?
8.  What is BER?
9.  What is RF?
10.  What is Modulation?
11.  What is the status of product development?
12.  I understand xMax can be used for both wired and wireless
applications. Why would wired applications be an attractive market?
13.  What government approval is required to operate xMax?
14.  For broadband wireless applications, how far can xMax transmissions reach?
15.  What steps have been taken to protect xMax?
16.  What problem does xMax solve for wireless applications?
17.  What applications can xMax be used for?
18.  What testing and validation has been done on xMax?
19.  What is the error correction scheme used in FSK, QAM, AFSK, PSK
or other modulation schemes?
20.  What is the BER (bit-error-rate) of xMax for different values of S/Nr?
21.  Does xMax require more transmitter power than other technologies?

Questions & Answers:

1. Q: Is the name xG meant to imply a comparison with 3G wireless technology?

    A: Yes. xG Technology, LLC intelligently pushes radio technology
to its theoretical limits - far beyond that of third generation (3G)
or even fourth generation (4G) technologies. Hence, the name xG, or
Xth generation. xG Technology also produces performance improvements
over other technologies in multiples – 10x, 20x, 30x, 100x. That's
another reason for the name. To be clear, 3G and 4G wireless
technologies don't directly define modulation systems, so the
comparison made here is to the core modulation techniques used in
those technologies.

Top of the page

2. Q: What is xMax?

    A: xMax is a novel modulation and encoding technology that boosts
the data rates of all wired and wireless communications.  xMax is not
a compression technique, but rather a synergistic mix of two
well-established communication approaches that dramatically improves
spectrum utilization.  By combining elements of traditional narrowband
carrier systems with non-interfering elements found in low-power
wideband systems, xMax delivers data rates orders of magnitude higher
than other broadband approaches.

Click HERE for a spectrum plot showing a test xMax signal.

The technology's name has been recently changed from xG Coded
Modulation (xGCMTM) to xMax as it prepares to leave the laboratory for
the marketplace.

Top of the page

3. Q: What is xG Flash Signaling?

    A: xG Flash Signaling is the micro power wideband signal used by
xMax to convey information. xMax uses xG Flash Signaling to transmit
wideband data at power levels well below the static noise found in the
atmosphere. Because radio frequency (RF) receivers can only detect
signals above the noise floor, xG Flash Signals are completely
non-interfering to neighboring systems.

Since every radio technology produces similar emissions the Federal
Communications Commission (FCC) has set regulatory limits that prevent
one system from interfering with another's operation. xG Flash Signals
fall as much as 100,000 times below these regulated power limits and
up to 10,000 times below that of ultra wideband (UWB) emissions.

Top of the page

4. Q: What is Index-NTM?

    A: In addition to its advanced modulation technology, xMax uses a
unique encoding system that dramatically reduces sideband emissions
while multiplying the data throughput rate. This technique is called
Index-N.

Top of the page

5. Q: What is VaribandTM?

    A: xMax offers a feature called Variband. This can be useful to
adjust the data throughput rate on-the-fly.

Top of the page

6. Q: What is S/Nr?

    A: S/Nr stands for the Signal to Noise Ratio. Every communications
system is subject to interference by noise. Some systems are more
susceptible than others. The S/Nr test is a measure of the sensitivity
of the receiving system to noise. Eb/No is also a measure of signal
and noise. Our technical papers relate noise performance using both
S/Nr and Eb/No for the readers convenience.

Top of the page

"7. Q: What is Shannon's Law?"

"    A: Shannon's Law is the relationship between channel capacity C
(bits/sec) or maximum data rate, bandwidth B (Hz) and Signal to Noise
power ratio S/N, as summarized in the Shannon-Hartley Theorem: C = B
log 2 (1+S/N). The narrowband channel allocation that xMax uses to
coordinate reception of its wideband xG Flash Signal is not the
system's information-bearing bandwidth. xMax does not violate
Shannon's Law."

peace,
core